Apparatus for the continuous extraction of oils and soluble substances from solid materials

ABSTRACT

A cylindrical housing encloses a plurality of vertically stacked extractor sections each containing a plurality of baskets in vertical registry with baskets of the other sections, with the baskets all being stationary so that material to be processed passes in a vertical path down through each successive extractor section. Rotating screens and miscella collection pans are disposed beneath the baskets in each extractor section and form the bottom thereof, with the screens and pans having aligned openings which during rotation permit the material being processed to be passed from an upper basket to a lower basket in vertical registry therewith. A countercurrent flow miscella and solvent distribution and collection system supplies miscella or fresh solvent to the upper portion of each of the extractor sections above the baskets and rotates with the screen and collection pan to progressively apply the proper strength of miscella or solvent to each of the baskets in each of the extractor sections.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to process and apparatus for thecontinuous extraction of oils and soluble substances from solidmaterials through the use of solvents and, more particularly, to the useof a multi-stage extraction system in which extraction of the oils, etc.is accomplished while the material is moved from one station to anotherduring processing.

2. Prior Art

In the past, in order to increase the volume of material to be processedin solvent extraction equipment, which became necessary due to theability of other equipment in the total processing system to handlegreater volumes of processed material, it was necessary to increase thediameter of the cylindrical extractors since they were only single-stageextractors in which a plurality of baskets were disposed within acylindrical housing in a circular pattern. This was acceptable until thediameters of the extractors became so large that they could notconveniently be shipped from the site of fabrication to the plantlocation where they would be utilized. This resulted in the necessity ofsome of the extractors being fabricated on site which was both costlyand inconvenient.

This initial difficulty was substantially overcome by the introductionof multiple-stage cylindrical extractors such as are commonly referredto as the carousel-type extractor as illustrated, for example, by DepmerU.S. Pat. No. 3,131,202. In this type of extraction device a pluralityof stages of extractors, each essentially identical to the prior artsingle-stage extractor, are stacked upon one another. The baskets ineach section are then rotated through almost 360° and then dumped intothe subsequent baskets beneath, in sequence, and these are then againrotated so that the varying strengths of miscella and solvent can beapplied to the baskets. In this manner, a higher volume of material canbe processed merely by adding an additional stage to the extractorwithout increasing its diameter, which thus permits the extractors to bemanufactured and shipped more easily.

Unfortunately, because of the substantial weight of the basketscontaining the large volumes of material being processed, a substantialamount of energy is utilized to rotate these baskets.

SUMMARY OF THE INVENTION

The present invention overcomes the above described difficulties anddisadvantages associated with prior art devices as well as many otherproblems, by providing a multiple-stage vertical solvent extractionapparatus in which the material being processed remains stationary inthe baskets in each stage and is then subsequently dumped in a verticalpath into each subsequent lower stage so that it is not necessary torotate the baskets containing the processed material and thus,substantial power savings occur. This is accomplished by the use of arotating screen which forms the basket bottoms in each section, alongwith the use of a rotating miscella collection pan and miscelladistribution system which rotates above the baskets in each stage tosupply varying strengths of miscella to the material being processed ineach of the stationary baskets. An opening in each of the screens andthe collection pan provides a through path for the material beingprocessed to a subsequent stage so that each basket in a stage issequentially dumped into the subsequent stage basket vertically beneathit after it has been treated with solvent and miscella which has beencollected in the respective collection pan.

In the process of the present invention, material from which the oils orother soluble substances are to be extracted are first placed in aplurality first stage stationary baskets. Miscella is then introducedinto each of the baskets and passes downwardly through the material toenhance the miscella. The enhanced miscella is then sequentially removedfrom each basket through a screen in the lower portion thereof anddropped into a second stage of stationary baskets wherein each baskettherein is in vertical alignment with a corresponding basket in thefirst stage.

Miscella is then introduced into the material in the baskets in thesecond stage and passes downwardly through the material being processedto further enhance the miscella. The miscella from each of the secondstage baskets then passes through a screen in the lower portion thereofand, again, the material being processed is sequentially dumped intofurther baskets in at least one further stage of stationary basketswherein the treatment steps are again repeated until a last of thesefurther stages is reached.

Thereupon, solvent is introduced into the baskets of the last stage toproduce miscella. This miscella in the last stage is then introducedinto a previous stage to further enhance it, and subsequently each stageabove the previous stage until the fully enhanced miscella is removedfrom the uppermost stage. The processed material in the last stage isthen dropped through the screens in the bottom thereof into a collectiondevice for removal and possible subsequent processing.

In the preferred form of the process of the present invention, thescreens beneath each of the stages are rotated and contain an openingthrough which each successive basket is opened to the basket in thesubsequent stage in alignment therewith so that the material beingprocessed can be sequentially dropped from stage to stage in a verticalpath after it has been treated with miscella or solvent in each stage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of the preferred embodiment of the presentinvention;

FIG. 2 is a vertical cross-sectional view of the upper two stages of theembodiment of FIG. 1;

FIG. 3 is a vertical cross-sectional view of the lower two stages andmaterial removal system of the embodiment of FIG. 1;

FIG. 4 is a horizontal cross-sectional view along the line 4--4 of FIG.1, showing the miscella distribution system and material distributiontrough in the first stage;

FIG. 5 is a horizontal cross-sectional view along the line 5--5 of FIG.1, illustrating the miscella distribution system for the second stage;

FIG. 6 is a horizontal cross-sectional view along the line 6--6 of FIG.1, showing the miscella distribution system for the third stage;

FIG. 7 is a horizontal cross-sectional view along the line 7--7 of FIG.1, illustrating the miscella distribution system of the fourth stage;and

FIG. 8 is a pictorial illustration of a collection pan exemplary of thecollection pan in each of the stages of the embodiment of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the preferred embodiment of the present invention as illustrated inFIG. 1, the multiple-stage extractor 10 is provided with four processingsections or stages indicated generally as stages 12, 14, 16 and 18,although the number of the stages can be varied in accordance with thedesired volume flow and depth of material to be processed. Beneath thelast stage 18 is the processed material removal stage 20 from which theslurry of flakes or other material which has been sequentially processedthrough each of the prior stages, is removed for subsequent processingfor disposal.

A single drive motor 22 drives all of the rotating apparatus in each ofthe stages through a gear reduction device 24, as described more fullybelow. The material to be processed is introduced through a feed screwconveyor 26 where it is introduced into the upper region of the firstextractor section 12.

Referring now to FIG. 2, the large arrows A indicate the direction offlow of the material to be processed as it is introduced through thefeed screw conveyor 26 and through a cylindrical spout 27 onto a trough28 which uniformly distributes the material in each of the baskets inthe first section 12 as the trough 28 is rotated in a circular pathabove the baskets. Each of the extractor sections or stages isconstructed essentially the same, with a cylindrical wall 30 forming themain outer housing of the apparatus, and an inner cylindrical concentricwall 32. Between these walls extend a plurality of vertically disposedradially extending partitions 34 which form the plurality of bottomlessbaskets therebetween.

Immediately beneath the concentric cylindrical walls 30 and 32, is adisc-shaped screen assembly 40 formed of a plurality of pie-shapedscreen segments 42, as shown in FIG. 4, for example, with an opening 44approximately .[.the extent of the bottoms of two of the baskets.]..Iadd.coextensive with the bottom of a basket .Iaddend.formed by thepartitions 34. This permits the material being processed to be passedfrom one extractor section to another sequentially from each basket.Each screen assembly 40 is supported in the upper region of acylindrical wall 46 which forms the outer wall of the miscellacollection pan 50. The bottom of the collection pan 50 is formed by aconically-shaped downwardly and outwardly extending disc 52 which joinsthe bottom edge of cylindrical wall 46.

As best seen in FIG. 8, a plurality of small openings 54 are providedaround the outer periphery of the collection pan 50 to permit themiscella to drain out of the collection pan and enter the miscelladistribution system as described below. A hopper 56 is formed in each ofthe miscella collection pans 50 by providing two vertically extendingpartitions 58 and 60 which extend from a central region of the panoutwardly to meet the cylindrical wall 46 to provide the pie-shapedopening of the hopper 56.

The bottom 52 of the pan 50 is interrupted at that point and thepartitions 58 and 60 extend downwardly through the bottom of the pan, asbest seen in FIG. 3, so that a trough is formed to direct the materialbeing processed either into the subsequent basket, or into the materialremoval section 20 in the case of the last stage. It is to be noted thatthe hoppers 56 in the sections other than section 18 are not seen inFIG. 2 since in the relative positions of the hoppers of the varioussections, as shown by FIGS. 4 through 7, the hopper is in front of thesection lines.

Referring again to FIG. 2, an annular ring 62 is welded to the outsideof cylindrical wall 46 and is provided with a plurality of stiffeningwebs 64. The annular ring 62 supports the miscella collection pan 50 andscreen assembly 40 around the outer periphery of the pan. A plurality ofroller assemblies 66 are mounted at equally angularly spaced locationsaround the outer periphery of the apparatus with the annular ring 62riding on the rollers 68 thereof. The support roller assemblies 66 areeach mounted to a support plate 70 which, in turn, is welded to the sideof a cylindrical wall 72 which extends completely around the juncture ofadjacent extractor sections. This juncture area is enclosed by upper andlower annular rings 73 and 74, which are welded on their inside edges tothe cylindrical walls 30 of the respective extractor section and weldedat their outside edges to wall 72.

A cylindrical ring 76 is welded to and depends downwardly from thebottom 52 of miscella collection pan 50 and closely surrounds the upperedge of the cylindrical wall 30 of the next lower extractor section inorder to prevent the miscella or material being processed from passingthrough the gap which would otherwise exist in this area.

A collection trough 78 is formed by the cylindrical wall 72 and annularring 74 in the lower region of each of the extractor sections andreceives miscella from the plurality of openings 54 defined in the lowerportion of the collection pan 50. Miscella distribution pipes connect tothe bottom of each of the troughs 78 which, for each extractor section,distributes the miscella to either a preceeding extractor section or toa collection tank when the miscella is completely enhanced, as isexplained more fully below.

The miscella or solvent is distributed over the upper portion of thebaskets in each extractor section by a plurality of miscelladistribution troughs 92 which extend radially outwardly at predeterminedangular locations from a central cylindrical trough 84, as seen for eachsection in FIGS. 4 through 7. It is to be noted that the miscelladistribution system for the first extractor section 12 is somewhatdifferent in that the troughs 82 are connected to the centralcylindrical trough 84 through interconnecting pipes 85 which alsosupport the troughs 82. In the other sections, the troughs 82 aredirectly connected to the central cylindrical trough 84 as shown.

All of the miscella distribution troughs, screen assemblies 40 andmiscella collection pans 50 are mounted to a central shaft 86 forrotation therewith. In addition, the material distribution trough 28 isalso mounted to the upper end of shaft 86 for rotation therewith. Thelower end of shaft 86 is supported in a hub 88, as shown in FIG. 3,which additionally supports the collection pan 50 and screen assembly 40of the last extractor section 18. In this last section, the miscellacollection trough 78 formed by the cylindrical wall 72 and upper andlower annular rings 73 and 74, is somewhat expanded in order toaccommodate a ring gear 90 which is supported by an also expandedannular ring 62, for rotation therewith. The gear reduction unit 24 andmotor 22 then, through a pinion gear 92, rotates the ring gear 90 whichthus simultaneously rotates all of the miscella distribution troughs,screen assemblies and miscella collection pan.

Referring now to the material removal stage 20, the hopper 56 in thelast extractor stage 18 empties directly into a conical chute 94 whichdirects the material towards a horizontally extending pair of miscellaextraction screws 96 and 98 which convey the material out of theapparatus. In doing so, however, the extraction screws 96 and 98 are sodesigned and positioned that they tend to squeeze the material to thusremove further miscella therefrom. This miscella passes through thescreen surface 100 beneath the screws and is collected in a furthercollection trough 102 from which it is removed by a miscelladistribution pipe 104 and pumped by pump 105 into miscella collectiontrough 78 of the last stage 18. Thus, additional miscella is removedfrom the material than would otherwise be the case if it were dumpedinto the hopper and simply removed. It is contemplated that other meansmay be utilized for removal of the material from beneath the conicalchute 94, such as a single feed screw or mechanical picker.

Referring now to the miscella collection and distribution system, asshown in FIGS. 2 and 3, the pure solvent, such as hexane, is introducedthrough a pipe 106 into the miscella distribution trough 84 from whichit then passes into the individual miscella distribution troughs 82. Asthe troughs 82 overfill, the miscella cascades over the sides of thetroughs and is thus applied to the upper surface of the material beingprocessed in each of the baskets as the troughs 82 are rotated by theshaft 86.

As the thus applied solvent passes through the material, it extracts theoil or other soluble substances therefrom and passes through the screenassembly 40 beneath the bottom of the baskets and is collected in thecollection pan 50. It then passes through the openings 54 in the bottomof the collection pan 50 and enters the cylindrical collection trough 78beneath the last stage extractor 18. From there it passes into the pipe108 and is pumped by pump 110 up to the upper region of the previousextraction stage 16 where it is introduced into the cylindrical miscelladistribution trough 84 and hence through the troughs 82 onto thematerial in the baskets. This miscella, as it passes through thematerial in the baskets is again further enhanced and collected in thecollection pan 50 where, as before, it passes into the collection trough78.

This now enhanced miscella is taken through the pipe 112 and pumped bypump 114 up to the next previous stage, as shown in FIG. 2, through pipe116 and is introduced into the upper region of extractor stage 14through the central cylindrical miscella distribution trough 84 and theindividual distribution troughs 82. As before, it passes through thebeds of material and becomes further enhanced and is then subsequentlypumped to the first stage through pipe 118 and distributed over thematerial as before. The miscella from the first stage is then removed toa distillation system (not shown) through pipe 119.

The sections of the device shown in FIGS. 4 through 7 show that each ofthe sets of miscella distribution troughs 82 are in a specificrelationship relative to those in the other stages, which is importantin processing material through the apparatus of the present invention.As shown in FIG. 4, the five miscella distribution troughs 82 arepositioned at equal angular locations behind the material distributiontrough in the direction of rotation, which is counterclockwise asviewed. Likewise, the screen assemblies 40 and the openings 44 thereinare in a specific relation between the various stages, with the opening44 being in advance of the material distribution trough in the firststage and being in the other stages in advance of the opening in thesubsequent immediately following stage.

As material is being introduced through the material distribution troughinto a basket, as illustrated in FIG. 4 in the first stage, thepreviously filled baskets are being treated with the previously enhancedmiscella. The last distribution trough 82 is somewhat in advance of theopening 44 in the screen so as to permit the miscella to drain throughthe material being processed before the opening 44 allows the materialto pass into the basket in the subsequent stage positioned immediatelybelow the basket being emptied. When the opening 44 in the first stagescreen assembly is positioned as illustrated in FIG. 4, the opening 44in the screen assembly of the second stage is positioned as illustratedin FIG. 5 so that the screen in the second section will cover the bottomof the basket in which the material being processed is received from thefirst extractor section.

It is also to be noted that the troughs 82 in FIG. 5 have not yetreached the position where the material is being passed from the firststage to the second, in order that it does not interfere with thepassage of the material. Also, it is to be noted that the opening in thescreen of the second stage immediately precedes, in the direction ofrotation, the opening in the screen of the first stage so that thematerial in the second stage is being dumped just prior to new materialbeing received from the first stage. All subsequent stages are similarlyaligned in regard to the openings 44 in the screen assemblies as well asthe positioning of the miscella distribution troughs 82, so thatmaterial is fully processed and the miscella removed through each cycleof rotation of the miscella distribution trough, material distributiontrough and screen assemblies.

It is to be noted that the hoppers 56 in each of the collection pans 50remain in alignment with the openings 44 in each of the screenassemblies in order to permit the material to be passed from one basketto a subsequent one in vertical registry therewith.

While the process and apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited thereby and that changes may be made therein withoutdeparting from the scope of the invention.

What is claimed is:
 1. In a continuous solvent extracting apparatus,having a cylindrical housing, material distribution means in an upperportion of said housing, a plurality of vertically stacked extractorsections each including a plurality of vertically disposed radiallyextending walls for receiving material therebetween from said materialdistribution means, screening means beneath said walls for retainingprocessed material in a section and passing miscella therethrough, acollecting pan associated with and beneath each screening means forcollecting miscella passed therethrough, miscella distribution means forremoving miscella from said pans and supplying miscella to an upperportion of each section and material removal means for removing materialfrom a lowermost extractor section, wherein the improvementcomprises:said plurality of walls are stationary and abut said housingwith each adjacent pair of walls and said housing forming a basket withsaid baskets in each section being in registry with said baskets in allother sections; each said screening means being horizontally disposed,disc-shaped, mounted for rotation and having an opening defined thereingenerally co-extensive with a basket when in registry therewith; eachsaid pan having an opening defined therein in alignment with saidopening defined in said associated screening mean for passing materialfrom a basket of one section to a basket of a subsequent section andmounted for rotation with said associated screening means; and means forrotating each said associated screening means and said pansimultaneously.
 2. The improvement of claim 1 wherein said means forrotating said screening means and pans includes means interconnectingall of said screening means and pans of all of said sections forsimultaneous rotation thereof.
 3. A continuous solvent extractingapparatus comprising:a cylindrical vertically extending housing; aplurality of vertically stacked extractor sections disposed within saidhousing each section having (a) a plurality of vertically disposedradially extending stationary walls extending outwardly and abuttingsaid housing with adjacent pairs of walls and the housing each defininga basket, (b) a horizontally disposed disc-shaped screen having anopening defined therein generally co-extensive with a basket when inregistry therewith and mounted for rotation beneath said walls, (c) amiscella collecting pan disposed beneath said screen and having a hopperdefined therein extending toward a top portion of a subsequent extractorsection and in alignment with said opening in said screen for passingmaterial vertically downward from a basket of one section to a basket ofthe subsequent section, (d) means for simultaneously rotating saidscreen and said pan; a material .[.collecting.]. .Iadd.removal.Iaddend.means disposed beneath a lowermost extractor section forremoving material from the apparatus after it has passed therethrough; amiscella distribution means for conveying miscella from said pan of anextractor section to a top portion of a previous extractor section abovethe one from which removed, and for removing miscella from an uppermostextractor section for distribution to a remote location; and means abovesaid lowermost extractor section for supplying solvent to a top portionthereof.
 4. Apparatus as defined in claim 3 wherein said material.[.collection.]. .Iadd.removal .Iaddend.means includes means for furtherextracting miscella from material being processed.
 5. Apparatus asdefined in claim 4 wherein said .[.further extraction.]. .Iadd.materialremoval .Iaddend.means includes .Iadd.means for .Iaddend.returning themiscella thus extracted to said .[.uppermost.]. .Iadd.lowermost.Iaddend.extractor section for mixing with miscella from that section.6. Apparatus as defined in claim 4 .[.or 5.]. wherein said .[.furtherextraction.]. .Iadd.material removal .Iaddend.means includes:afunnel-shaped housing extending downward from said lowermost extractorsection; a pair of horizontally extending intermeshing screw flightsdisposed beneath said funnel-shaped housing and co-operating to expelprocessed material from the apparatus; a further screen disposed beneathsaid screw flights through which miscella can pass; and a .[.miscellareceiving means.]. .Iadd.collection trough .Iaddend.disposed beneathsaid further screen for receiving miscella therefrom.
 7. Apparatus asdefined in claim 3 wherein said means for rotating said screens and saidpans includes means interconnecting all of said screens and pans in allof said sections for simultaneous rotation thereof. .Iadd.8. Anapparatus as defined in claim 5 wherein said material removal meansincludes:a funnel-shaped housing extending downward from said lowermostextractor section; a pair of horizontally extending intermeshing screwflights disposed beneath said funnel-shaped housing and co-operating toexpel processed material from the apparatus; a further screen disposedbeneath said screw flights through which miscella can pass; and acollection trough disposed beneath said further screen for receivingmiscella therefrom. .Iaddend.